U-folds as K3 fibrations

Abstract

We study N=2 four-dimensional flux vacua describing intrinsic non-perturbative systems of 3 and 7 branes in type IIB string theory. The solutions are described as compactifications of a G(ravity) theory on a Calabi Yau threefold which consists of a fibration of an auxiliary K3 surface over an S^2 base. In the spirit of F-theory, the complex structure of the K3 surface varying over the base codifies the details of the fluxes, the dilaton and the warp factors in type IIB string theory. We discuss in detail some simple examples of geometric and non-geometric solutions where the precise flux/geometry dictionary can be explicitly worked out. In particular, we describe non-geometric T-fold solutions exhibiting non-trivial T-duality monodromies exchanging 3- and 7-branes.

30 pages, 4 figures, v2: typos corrected, comments added, references added

References in corpus (10)

• Double Field Theory
• GUTs and Exceptional Branes in F-theory - II: Experimental Predictions
• Double Field Theory: A Pedagogical Review
• Les Houches Lectures on Constructing String Vacua
• New Aspects of Heterotic--F Theory Duality
• D7-Brane Motion from M-Theory Cycles and Obstructions in the Weak Coupling Limit
• E11, generalised space-time and IIA string theory
• E11, generalised space-time and IIA string theory; the R-R sector
• Geometries, Non-Geometries, and Fluxes
• Semi-Flatland

Cited by in corpus (10)

• An Action for F-theory: $\mathrm{SL}(2)\times {\mathbb{R}}^{+}$ Exceptional Field Theory
• K3 surfaces, modular forms, and non-geometric heterotic compactifications
• Exceptional $\mathcal{N}=3$ theories
• Type IIB flux vacua from G-theory II
• Infinitely Many M2-instanton Corrections to M-theory on $G_2$-manifolds
• Nongeometric heterotic strings and dual F-theory with enhanced gauge groups
• NS5-Branes and Line Bundles in Heterotic/F-Theory Duality
• Meromorphic Flux Compactification
• A class of non-geometric M-theory compactification backgrounds
• Duality Covariant Solutions in Extended Field Theories